DESCRIPTION: (Verbatim from application) Revised Application: Because the specific causes underlying low back pain LBP have not yet been identified, it continues to be a significant public health problem. Many of the factors associated with low-back pain are mechanical in nature. Epidemiological and biomechanical studies have suggested that there is a link between sudden and unexpected loading, such as slips and falls, and low-back injuries. Under these circumstances, motor control of the mechanical stability of the lumbar spine is crucial in determining trunk kinematic response to sudden loading and the subsequent likelihood of injury. Compared to healthy controls, however, LBP patients exhibit deficits in motor control such as delayed trunk muscle reflex response, poor trunk positioning sense, and impaired postural control. These deficits may constitute predisposing risk factors for sustaining an injury, a compensation/pain avoidance mechanism, or they may be the consequence of damage sustained by the lumbar spine tissues. The objective of the proposed research is to improve our understanding of the relationship between the measured motor control deficit and LBP. Two experimental studies and a post-hoc analysis of the entire data set form the 3 specific aims. The first prospective design study will consist of the initial testing and a 2-year follow-up of varsity athletes. The goal is to determine whether poor motor control of the lumbar spine increases the risk for sustaining a low-back injury. The second randomized prospective study will be conducted to document the changes in motor control of the lumbar spine in LBP patients before and after standard and modified rehabilitation programs that emphasize motor control training. Several tests, developed in preliminary studies, will quantify the deficit in the motor control in LBP individuals: response of trunk muscles to a sudden, multi-directional load release and the stability of the lumbar spine, and postural control of the trunk in unstable sitting. Correlations between the above measures of motor control and other variables in the LBP population will be determined in the third specific aim. These additional variables will include: trunk position and motion proprioception, objective and subjective measures of physical function, diagnosis and duration of symptoms, and personal characteristics such as age and gender. The results of the proposed research will have a significant clinical relevance for designing more effective prevention, diagnosis, and rehabilitation strategies for LBP.